219644-97-0Relevant articles and documents
[3,3]-Sigmatropic rearrangement step in the gold-catalyzed cyclization of allyl-(ortho-alkinylphenyl)methyl ethers
Ackermann, Martin,Bucher, Janina,Rappold, Melissa,Graf, Katharina,Rominger, Frank,Hashmi, A. Stephen K.
supporting information, p. 1786 - 1794 (2013/09/02)
The gold-catalyzed conversion of allyl-(ortho-alkynylphenyl)methyl ethers was investigated, and allylated isochromenes were obtained. An optimization of the catalysis conditions with respect to different phosphane and carbene ligands on gold, different counterions, and different solvents was conducted. Subsequently, the scope and limitations of this reaction were investigated with 21 substrates. The mechanistic studies show an allylic inversion, as supported by NMR data and an X-ray crystal structure analysis, as well as an intermolecular reaction, as determined by crossover experiments. There is no competition of protodeauration even in the presence of water. All these observations differ from other related conversions and clearly indicate product formation by a [3,3]sigmatropic rearrangement in the step forming the new C-C bond. The Golden Key: Allylic inversion and crossover experiments reveal a sigmatropic rearrangement as a key step in the gold-catalyzed intramolecular allyl transfer in ortho-alkinyl benzyl allyl ethers. Copyright
Palladium-catalyzed cross-coupling of 2,5-cyclohexadienyl-substituted aryl or vinylic iodides and carbon or heteroatom nucleophiles
Larock, Richard C.,Han, Xiaojun
, p. 1875 - 1887 (2007/10/03)
2,5-Cyclohexadienyl-substituted aryl or vinylic iodides have been reacted with carbon nucleophiles (diethyl malonate and 2-methyl-1,3- cyclohexanedione), nitrogen nucleophiles (morpholine, potassium phthalimide, N-benzyl tosylamide, di-tert-butyl iminodicarboxylate, lithium azide, and anilines), a sulfur nucleophile (sodium benzenesulfinate), and oxygen nucleophiles (lithium acetate and phenols) to afford products of cyclization and subsequent cross-coupling in good to excellent yields. In most cases, this process is highly diastereoselective. The reaction is believed to proceed via (1) oxidative addition of the aryl or vinylic iodide to Pd(0), (2) organopalladium addition to one of the carbon-carbon double bonds, (3) palladium migration along the carbon chain on the same face of the ring to form a π-allylpalladium intermediate, and (4) nucleophilic displacement of the palladium.
